This invention relates to a method and apparatus for assaying a fluid sample to detect the presence or absence of a chemical or biochemical constituent in the sample or in the surrounding environment.
At the present time fluid samples are tested in a variety of apparatus for various constituents including specifically reactive pairs such as antibody-antigen pairs, enzyme-substrate pairs, D.N.A. fragment pairs, R.N.A. fragment pairs and the like. It is common practice to immobilize a reactant for the constitutent being tested on a support surface and then contacting the fluid sample with the coreactant. The constitutent is allowed to react with the coreactant to determine the presence, and, in some cases, the concentration of the constituent in the sample. Examples of assays which permit determination of the constituent concentration include the enzyme-linked immunosorbent assay (E.L.I.S.A.) and the radioimmunoassay (R.I.A.)
In these procedures, filter materials such as microporous or ultrafiltration membrane, nonwovens, papers, glass fibers, or other filter materials membranes provide a desirable immobilizing support for biologically active constituents since separation of the constituent for which the test is conducted can be easily effected. Examples of suitable membranes are disclosed in U.S. Pat. No. 4,066,512. Suitable apparatus utilizing these and other membranes to effect fluid sample assays are described in U.S. Pat. Nos. 4,246,339; 4,526,690; 4,632,901; 4,727,019 and U.S. Pat. No. 4,737,192. While each of these apparatus provides the capability of conducting accurate fluid assays, each of these apparatus suffer from the same deficiencies. The primary deficiency is that they comprise multipiece constructions which require that the apparatus pieces be formed in a batch mode of construction such as by injection molding. Thereafter the pieces are assembled to form the final apparatus. Due to their design and method of assembly, these apparatus are expensive to produce.
Accordingly, it would be desirable to provide apparatus for effecting assays which can be produced by a continuous process and are of unitary construction so that they can be mass produced without the need for manual labor. Furthermore, it would be desirable to provide such an apparatus which can effect either immediate reaction or permit an incubation period for the reactants. In addition, it would be desirable to provide such an apparatus which renders it possible to effect a multistep reaction process with variable incubation times being permitted for each step. Furthermore, it would be desirable to provide such an apparatus which can include one or a plurality of discrete reaction zones. Such apparatus would provide a desired economy in production and a desired flexibility in use of assay apparatus.